REPRESENTATION THEORY AND RELATED TOPICS SEMINAR

ABSTRACT: We study the singularities of the Drinfeld-Lafforgue-Vinberg compactification of the moduli stack of G-bundles on a smooth projective curve for a reductive group G. The definition of this compactification is due to Drinfeld and relies on the Vinberg semigroup of G. We will mostly focus on the case G=SL_2; in this case the compactification can alternatively be viewed as a canonical one-parameter degeneration of the moduli space of SL_2-bundles. We then study the singularities of this one-parameter degeneration from a topological viewpoint. Time permitting, we might sketch the case of an arbitrary reductive group G and the relation to Langlands duality.